Environmental Health & Toxicology Flashcards

What term describes the highest dose at which no adverse effects are observed in a toxicology study?

Answer: NOAEL

NOAEL stands for No Observed Adverse Effect Level, the highest tested dose producing no statistically significant adverse effects.

Which route of exposure is typically most significant for volatile organic compounds (VOCs) in indoor environments?

Answer: Inhalation

VOCs readily vaporize at room temperature, making inhalation the dominant exposure route in enclosed indoor spaces.

The LD50 toxicological value represents the dose lethal to what percentage of a test population?

Answer: 50%

LD50 (Lethal Dose 50) is the dose required to kill exactly 50% of the test population under specified conditions.

Which of the following best describes bioaccumulation?

Answer: The progressive increase in concentration of a substance within an organism over time

Bioaccumulation refers to the buildup of a substance within a single organism faster than it can be eliminated or metabolized.

In risk assessment, the Reference Dose (RfD) is primarily used to evaluate:

Answer: Acceptable daily intake thresholds for non-carcinogenic chemicals

The RfD is an EPA estimate of a daily oral exposure to a non-carcinogen that is unlikely to cause appreciable risk over a lifetime.

Which federal agency establishes Maximum Contaminant Levels (MCLs) for public drinking water systems?

Answer: U.S. EPA

The U.S. EPA sets MCLs under the Safe Drinking Water Act (SDWA) to protect public health from contaminants in drinking water.

Biomagnification differs from bioaccumulation primarily because it describes:

Answer: Progressive increase in chemical concentrations at successively higher trophic levels in a food web

Biomagnification specifically refers to the amplification of contaminant concentrations as they move up through food chain trophic levels.